Hemorrhoids are protrusions, bulges, folds, or irregularities of anal tissue, both inside the anal verge and outside on the anal margin. They are composed of epithelial lining (skin or mucus membrane), connective tissue and blood vessels in varying proportions. The dentate line, a distinct band normally located within the anal canal, marks the transition from columnar rectal mucosa to squamous anoderm. Hemorrhoids above the dentate line are referred to as “internal hemorrhoids”, and hemorrhoids distal to the dentate line are called “external hemorrhoids”. When internal hemorrhoids protrude beyond the anal verge, they are said to “prolapse”. The entire circumference of the anus may be affected by hemorrhoids, or hemorrhoids may be restricted to one or two “quadrants” or sectors. Sometimes normal appearing lining of the upper anus and low rectum protrudes beyond the anal verge, a condition referred to as “mucosal prolapse.”
Hemorrhoids are formed by the stress produced by bowel movements, straining and local irritation. Factors which contribute to the development of hemorrhoids may include aging, chronic constipation or diarrhea, pregnancy and heredity.
Hemorrhoids warrant treatment because of the symptoms they produce, including itching, bleeding, discharge, discomfort, and pain.
There are a number of known techniques used in the surgical treatment of hemorrhoids. These techniques include the excision or destruction of the hemorrhoidal tissue using scissors or scalpel, laser or infrared light, electricity or heat. Injection sclerotherapy is another treatment. Hemorrhoids may also be strangulated with ligatures, using small rubber rings (“rubber band ligation”) or using sutures (“obliterative suture technique”).
More recently, another procedure for the treatment of hemorrhoids has been developed whereby a circular stapler is used to remove a ring of anorectal tissue just above the hemorrhoids. This pulls the hemorrhoids back within the anus, flattens the hemorrhoids to some degree, and partially interrupts their blood supply, thereby rendering the hemorrhoids less symptomatic. This procedure is known as the “Procedure for Prolapse and Hemorrhoids (PPH)”.
The instrument developed for use in the PPH operation consists of a modified circular endoluminal stapler, the stapler being sold under the name Proximate HCS™ (Hemorrhoidal Circular Stapler) by Ethicon Endo-Surgery, Inc. The instrument is described in U.S. Pat. No. 6,102,271, the method for its use is described in U.S. Pat. No. 6,083,241 and a special anoscope adapted to facilitate the performance of the procedure is described in U.S. Pat. No. 6,142,933. The disclosures of U.S. Pat. Nos. 6,102,271, 6,083,241 and 6,142,933 are hereby incorporated herein by reference.
The stapling instrument 25 disclosed in U.S. Pat. No. 6,102,271 (hereinafter “the '271 patent”) conventionally includes a handle 30, a firing trigger 32 and an anvil closure knob 31 located at a proximal end of the device that is operatively coupled to an anvil assembly 60 such that the rotation of the knob 31 moves the anvil assembly 60 proximally or distally depending on the direction of rotation of the knob. Extending from the handle is a circular shaft 35 that is coupled at a distal end thereof to a circular stapling head assembly 41 for delivering a plurality of staples in a circular arrangement and simultaneously cutting the hemorrhoidal tissue upon actuation of the firing trigger 32.
The PPH operation using the stapling instrument described in the '271 patent is described in U.S. Pat. No. 6,083,241 (hereinafter “the '241 patent”). The procedure described in the '241 patent generally includes the following steps: a circular anal dilator 100 is inserted into the anus and the sheath of the anal dilator 100 is sutured to the perianal skin with silk sutures. Thereafter, an anoscope 120 is inserted within the anal dilator 100 and a purse-string suture 27 is sutured into the lining of the anorectum circumferentially at a location above the internal hemorrhoids. The anoscope 120 is removed and the open stapling instrument 25 is inserted into the anorectum. As the instrument 25 is inserted into the anorectum, the anvil assembly 60 passes through the pursed-stringed bowel. The surgeon then ties the purse-string drawing the anorectal lining around the shaft of the instrument 25 between the anvil assembly 60 and stapling head assembly 41. The surgeon then draws the ends of the tied purse-string suture through the barrel of the stapling head assembly 41, one on each side of the instrument 25. The ends of the purse-string are then tied together to form a loop. The surgeon closes the instrument 25 while maintaining tension on the loop of the purse-string suture 27, which helps draw the hemorrhoidal tissue inward into the barrel of the instrument 25. Closing the instrument 25 moves the anvil assembly 60 from the open position spaced from the stapling head assembly 41 to a closed position adjacent to the stapling head assembly 41 to clamp the hemorrhoidal tissue between the stapling head assembly 41 and the anvil assembly 60. The circular stapling instrument 25 is then fired to simultaneously cut and staple the hemorrhoidal tissue.
The PPH operation described above has some inherent shortcomings. First, the actions of forming the purse-string suture, tying the purse-string suture around the anvil shaft, and drawing the ends of the purse-string suture through the head of the stapling instrument are relatively difficult and manually intensive. Second, the surgeon must rely only on the purse-string and tension on the purse string to draw anorectal tissue into the instrument. Third, the surgeon cannot easily monitor the amount of hemorrhoidal tissue that is drawn into the stapling instrument because as the instrument closes his view is blocked by the stapling head assembly. Fourth, the amount of hemorrhoidal tissue excised is limited to the quantity of tissue that can be drawn into the barrel of the instrument. Fifth, the quantity of tissue drawn into the instrument and excised is inconsistent from case to case and is dependent upon multiple factors, including the skill with which the purse-string suture is placed, the level at which the purse-string suture is placed, the degree of prolapse, the disposition of hemorrhoids in the particular patient, the amount of anorectal inflammation present, the tension placed on the purse-string loop, and the orientation, or angulation of the stapler.
The amount, thickness and shape of the hemorrhoidal tissue can vary around the circumference of the rectum. However, since the stapling head assembly 41 and the anvil assembly 60 of the device disclosed in the '271 patent are rigid circular structures, the amount of hemorrhoidal tissue removed in a given sector of the rectum cannot be individually selected. This may result in inadequate treatment of the hemorrhoid in a given sector of the rectum. Likewise, when there is only a single hemorrhoid or a hemorrhoid is located in only one particular sector of the rectum, the device disclosed in the '271 patent cannot be easily used to treat only that hemorrhoid or that particular sector of the rectum.
Another problem with the PPH operation is that, often, after the stapler is fired, the staple line has a tendency to bleed requiring additional sutures for hemostatis which prolongs the procedure. Also, the staple line may dehisce, meaning that the staples may not hold the ends of the lining of the bowel together which can result in bleeding and/or infection. Further, in female patients, it is possible that the vaginal lining may be entrapped in the staple line. If the staple line then fails, a communication can then develop between the rectum and the vagina, a condition called rectovaginal fistula, which can result in the passage of flatus or stool through the vagina.
Another problem with the PPH procedure is that scarring can occur at the staple line causing the rectum to narrow which can result in a stenosis. If the staple line is placed too high in the rectum, an hour-glass configuration of the rectum could result, causing interference with the passage of stool.
Other stapling instruments adapted for use in transanal procedures are also known. For example, U.S. Pat. No. 6,302,311 (hereinafter “the '311 patent”) describes a endoscopic stapler designed to achieve full thickness resection of a portion of the colonic wall. The endoscopic stapler 10 disclosed in the '311 patent includes a stapling head 12 and an attached sleeve 14 for feeding a conventional endoscope 16 therethrough. The stapling head 12 includes a stationary part 18 and a movable part 20. The endoscope 16 is fed through a portion of the sleeve 14 so that a distal end of the endoscope 16 resides in the stationary part 18 of the stapling head 12. The movable part 20 of the stapling head 12 includes a semi-circular anvil 48 and the stationary part 18 is adapted to fire a semi-circular double row of staples 32 and simultaneous cut the diseased tissue upon actuation of a control wire 22.
During use, the endoscopic stapler 10, together with the endoscope 16, are inserted into the anus, fed through the rectum and into the colon. A forceps instrument 26 is fed through a lumen in the endoscope 16 into the space between the stationary part 18 and the movable part 20 in order to enable the surgeon to pull tissue between the stationary part 18 and movable part 20. Once the tissue is arranged between the stationary part 18 and movable part 20, the movable part 20 is drawn towards the stationary part 18 by means of a control wire 24 until the tissue is grasped between the two parts 18 and 20. The control wire 22 is then used to fire the staples 32 from the stationary part 18 and simultaneously cut the tissue.
As noted above, the device disclosed in the '311 patent is primarily intended to be used to achieve full tissue resection of the colonic wall. Thus, the device is not specifically adapted to be used in hemorrhoidectomy procedures. Moreover, there are some structural features of the device disclosed in the '311 patent that make it ill-suited for such procedures. For example, as described above, in order to gain access to the tissue being removed, forceps 26 must be fed through a lumen in the endoscope 16. Thus, the surgeon does not have direct access to the tissue being treated making the procedure difficult. Moreover, in the device disclosed in the '311 patent, the movable part 20 and the stationary part 18 are interconnected by a central post 52, or three peripherally placed posts 352, 352 and 353, that would interfere with the surgeon's access to the bowel wall between the stationary part 18 and the movable part 20. Thus, when performing a hemorrhoidectomy, the posts would make it difficult to access the hemorrhoidal tissue and position the hemorrhoidal tissue between the stationary part 18 and movable part 20. Clearly, the embodiments shown in '311 patent are meant for use in conjunction with an endoscope, and are not designed to facilitate direct access to anorectal tissue.
Another use of the stapling instrument disclosed in the '271 patent is for the treatment of obstructive defecation. Obstructive defecation can be caused by the prolapse of the rectal lining within the rectum, rather than to the outside. Such prolapse can interfere with the passage of stool. The stapler disclosed in the '271 patent has been used in a procedure called Stapled Trans-Anal Rectal Resection (STARR) to remove a portion of the lining and thereby relieve obstructions. In this operation, the stapled of the '271 patent is used with a partial purse-string so that the mucosal lining of only a portion of the circumference of the rectum is captured within and removed by the instrument. However, such an effect could better be achieved by the invention disclosed herein as explained below.
U.S. Patent Publication No. 20040084505 shows a curved cutter stapler which, it is claimed, is useful for removal of tissue within the body cavity. The removal of rectal polyps, mucosal prolapse and rectoceles are potential uses sited in the patent. The use of this stapler for the specific treatment of hemorrhoids is not mentioned. However, this stapler has certain drawbacks. Since one longitudinal side of the stapling head is open, the opposite side must be strong enough, and therefore broad enough, to prevent movement of the anvil across its entire length, so that alignment will be maintained and staples properly formed. This makes the overall length of the stapling head large in comparison to the length of the staple line. As the angle of the arc increases, the more difficult it is for such a design to maintain alignment of the jaws upon closure of the instrument. As a result, the stapler becomes either unreliable, or unwieldy, and not suitable for use within the rectum. In addition, the handle of the stapler described in this patent publication is parallel to the plane of the middle of the arc of the stapling head, which makes it somewhat difficult to press against the wall of the rectum when holding the stapler by the handle alone. Furthermore, this stapler contains stapling lines on both sides of the blade. However, for use within the rectum to remove tissue from the wall, it would be preferable to have no staple lines only outside the curvature of the blade. In this situation it is not helpful to staple the tissue which will be removed, and doing so may make that tissue more difficult to remove. Stapling the tissue which is being removed would be particularly counterproductive if that tissue were a lesion which requires precise histologic examination.